Question

Match List I with List II
List I (Type of Spoilage):
A. Sweet curdling
B. Ropiness
C. Bitty cream
D. Fruit flavour
List II (Causative microorganism):
i. B. cereus var mycoides
ii. Streptococcus liquifaciens
iii. Pseudomonas fragi
iv. S. lactis var hollandicus
Choose the correct answer from the options given below:

• A. A – i, B – ii, C – iii, D – iv
• B. A – ii, B – iv, C – i, D – iii
• C. A – iv, B – iii, C – ii, D – i
• D. A – ii, B – iii, C – i, D – iv

Hint:

Remember that "bitty cream" is caused by lecithinase-producing Bacillus cereus, which damages the fat globule membrane and causes fat clumping.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Spoilage defects in dairy products are associated with specific microbial contaminants and their metabolic activities.

Step 2: Detailed Explanation:
Let us analyze the physiological and biochemical mechanisms for each match:
A. Sweet curdling is caused by Streptococcus liquifaciens (ii).
This organism is a proteolytic bacterium that produces a rennin-like extracellular enzyme.
This enzyme clots the milk at a neutral or slightly acidic pH without producing significant acid.
B. Ropiness is caused by Streptococcus lactis var. hollandicus (iv).
This variant produces extracellular mucilaginous polysaccharides, which form viscous, slime-like threads in milk.
C. Bitty cream is caused by Bacillus cereus var. mycoides (i).
This spore-former produces lecithinase, which hydrolyzes the lecithin in the milk fat globule membrane.
This causes the fat globules to coalesce and form floating "bits" or clumps on the surface of milk or cream.
D. Fruit flavour is caused by Pseudomonas fragi (iii).
This psychrotrophic bacterium hydrolyzes milk fats and proteins, producing volatile esters that impart a fruity odor.

Step 3: Final Answer:
Combining these pairs yields A – ii, B – iv, C – i, D – iii.